1. Field of the Invention
The present invention relates generally to electrophotographic imaging devices and, more particularly, to a method of adjusting transfer voltage in an image forming device based on temperature and humidity in conjunction with transfer feedback voltage.
2. Description of the Related Art
An electrophotographic imaging device uses electrostatic voltage differentials to promote the transfer of toner from component to component. In printers using an electrophotographic imaging device, toner is transferred by means of an electrostatic charge from the developer roll to the photo-conductor unit, and then from the photo-conductor unit to the paper. Paper is transported under the photo-conductor unit with a transfer belt. A metal transfer roll coated with a layer of foam sits under the transfer belt. A transfer voltage is applied to this transfer roll in order to move charged toner particles from the photo-conductor unit onto the paper.
The effective transfer of toner within an image forming device is usually dependent on many variables, including environmental conditions such as temperature and humidity. Changes in the temperature and humidity in an environment affect the electrical properties of printer components, which can have a significant impact on print quality.
Previous approaches to improving print quality by adjusting transfer voltage include using dedicated temperature and humidity sensors to detect environmental conditions. These devices may alter operating parameters, such as the transfer bias applied to a transfer member, in response to the detected environmental conditions. Another approach to improving print quality by adjusting transfer voltage includes using measured transfer voltage feedback loops in order to select an appropriate transfer voltage.
A common drawback of these approaches is that temperature and humidity measurements alone are not sufficient to completely characterize the electrical behavior of the system. Further, measured feedback voltages alone cannot adequately distinguish between environmental conditions.
Thus, there is still a need for an innovation that will use measurements from a temperature/humidity sensor in conjunction with measured feedback voltage measurements to adjust the transfer voltage.